Tachometer generator



March 31, 1931. f Q ANGUS 1,798,394

TACHOMETER GENERATOR Filed ont. 1s, 192s 2 sheets-sheet 1 March 31, 1931. D. J, ANGUs 1,798,394

TACHOMEIER GENERATOR Filed Oct. 13. 1928 '2 Sheets-Sheet 2 1555.7. i

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Patented Mar. 31, 1931 DONALD J'. l.AN(:`r`US, 0F INDIANAPQLIS, INDIANA.

TAHoMETER GENERATOR.

Application iiled October 13, 1928. Serial No. 312,321.

It is the object of my present invention to provide a rugged, reliable, and fool-proof tachometer generator.l

It is more especially the object of the present invention to provide a tachometer generator in which: i

1. The generator is free from danger of magnetic disturbances from being set on magnetic material.

2. The armature shaft is free from distortional strains from the driving connection. 3. The permanent magnets and pole-pieces are mounted so that they are free from torsional strains from the driving. 1l. The electrical and magnetic mechanism and the gearing are kept apart, by having the two in separate compartments, so that the electrical and magnetic mechanism may be kept Jfree from oil and grease.

5. All shafts are mounted so that the bearings or them may be prepared in a'single operation, and accurate parallelism obtained. 6. The cover is removable and replaceable without aifectingthe relation of the working parts; and when in place makes a water-r tight, oil-tight, and gas tight construction so that the generator may be safely used in places that would be impossible if working parts were exposed. 7. The commutator and brushes are substantially wear-proof.

8. The commutator and brushes are readily removablev and replaceable, by a simple operation which it is practically impossible to erform incorrectly.

he accompanying drawings illustrate my invention: Fig. 1 is a partial end elevation and partial vertical section on the line 1--1 of Fig. 2 of a tachometer generator embodying my invention; Fig. 2 is a vertical longitudinal section substantially on the line 2-2 of Fig. 1; Fig. 3 is a horizontal section substantially on the line 3 3 of Fig. 2; Fig. 4; is a horizontal section substantially on the line 4.-4 of Fig. 2; Fig. 5 is a vertical transverse section substantially on the line 5-5 of Fig. 2; Fig. 6 is a vertical transverse section substantially on the line 6-'6 of Fig. 2; Fig. 7 is an enlarged plan of the lower casing member, with the shafts, armature, and gearing removed, and with the permanent magnets and pole-pieces in horizontal section substan tially as in Fig. L1; Fig.

8 is an enlarged vertical section transverse to the armature shaft showing the commutator in section and the brushes in position,

and illustrating how the brushes are gripped for removing and replacing them; Fig. 9 is a sectional view somewhat similar to' Fig. v8, but showing how the brushes are manipulated in the process of their removal or replacement; Fig. 10 is an elevation of one of the brushes, showing the commutator-engaging side; Fig. 11 is a View viewed from the side away from thecommutator; Fig. 12 is a longitudinal section through the commutator before it is ground, and is taken substantially on theline 1212 of Fig. 13;

Fig. 13 is a transverse section on the line 13-13 of Fig. 12; and Fi 14 is a section generally similar to Fig. 12, ut showing the commutator after it has been vground to its final form.

The casing comprises a lower part 20 and an upper part 21, and the lower part 20 of the f casing has a vertical partition 22 which divides the casing into a gearing compartment 23 and an electro-magnetic compartment 24. The two casing parts 20 and 21 meet on a horizontal plane 25, where there is a gasket which provides a water-tight oil-tight, and gas-tight joint when the two parts are fastened together by the clamping screws 26.

The partition 22 extends upwardbeyond the parting plane 25 into the upper casing-part v 21, and forms with the latter a substantially oil-tight ]oint by reason of pacln'ng 27 which lies between two internal iianges 28 on the upper casing part or cover 21. All the working parts are carried 20.; so that the cover by the lower casing-part 21 may be removed without affecting such working parts.

The magnetic eld of the generator is furnished by a permanent magnet 30, which is of the usual horseshoe shape but has its poles important upward. This position of the magnet 30 is for it prevents magnetic interference with the field of the permanent magnet from magnetic material on which the generator may be set. The poles "of the magnet of one of the brushes and its mounting, as

30 are fastened by screws to pole-pieces 31. The pole-pieces 31 are fastened by screws to the adjacent side of the partition 22, near the j upper end of the latter; the partition being faced on the surface 32 to receive accurately the machined end faces of the pole-pieces, and such surface 32 having a circular rib 33 projecting therefrom just inside of the polepieces to position them on the partition. The

opposite ends of the pole-pieces 31 abut against and carry a plate 34, which is alsofaced and provided with a positioning ring 35 to fit in accurateA position againstsuch pole-pieces. Theplate 34 carries a bearing yoke 36, which is integral therewith, for supporting one end of the shaft 37 which carries the armature 38 and commutator 39.

. The permanent magnet 30 is hung entirely from its upper end, and by the pole-pieces 31, and is spaced from all other parts, such asthe lower casing-part 20 and the Apartition 22. This relieves the permanent magnet 30 from all stresses, and thus prevents the-transmisj sion therethrough of mechanical stresses to the pole-pieces 31; because said pole-pieces are desirabl ground internally to a definite clearance rom the armature, and such mechanical stresses would tend to get them out of true.

. The 4armature shaft 37 is mounted in ball bearings in the yoke 36 and in the partition 22; and projects through such partition, and carries a pinion 40 on its end in the gearing compartment 23. Such pinion 40 meshes with the gear 41 on the end of a jack shaft 42,` which is mounted in ball bearings in the'end of the casing part 20 and in the partition 22. Thus the gearing -41 is located entirely in the compartment 23; and any oilor grease therefrom is kept away from the electrical and magnetic apparatus.

The jack shaft 42 projects beyond the left- 4hand end (Fig. 2) of the casing-20-21, and is provided with a packing gland 43 between the adjacent ball-bearing and the exterior. The exposed end of the jack shaft 42 receives power, in any suitable manner, from the device whose speed is to be measured as shown being provided with a shoulder against which a gear or pulley may be clamped by a nut 44.

In assembling the parts, the holes for both the ball bearings and the gland of the jack shaft 42 may be machined in one operation, and `the surface 32 may be faced and the hole for the right-hand ball bearing (Fig. 2) of the armature shaft 37 may be machined in one operation, all in the same machine without changing the setting of the casing-part 20; for allthese machined surfaces are' on that casing-part, and all of them are machineable about parallel axes. This makes for -acglrate parallelism between the shafts 42 and However, all-strains from the driving are ture shaft 37 and the whole-electro-magnetic mechanism are free from strains from the driving.

In order to control the fiux in which the armature 38 rotates, -I desirably provide an adjustable magnetic shunt 45 extending between the two magnet poles with a variable air gap between it and one of them. For this purpose, the magnetic shunt 45 has one end restino on one pole of the magnet 30, held there by a compression. spring 46 acting between the head of an attaching screw and said magnetic shunt; and the other end is adjustably held away from the other pole of the magnet, as by a thrust screw 47.

'The exterior of the armature is desirably ground accurately, to get an accurate air gap between it and the ground pole-pieces 31.

The commutator 39, which is also mounted on the shaft 37, has a peculiar construction. It can perhaps best be described by describing how it is made. A ring 50 of insulating material, conveniently bakelite, has an axial hole 51, which is of such sizethat it has a driving lit on the armature shaft 37 `It--also has a circular series of holes, equiangularly spaced apart, around the axis of the hole 51 as a center, for receiving a series of glasshard high-carbon steel rods 52. Two binding rings 53, of metal, desirably fit over the end portions of the ring 50, to reinforce it in construction and operation. The construction so far described is shown in Figs. 12 and 13, and is a unit of manufacture. This unit is driven on to the desired position on the armature shaft 37 and then the middle part of the unit, between the two rings 53, is ground away about to the middles of the rods 52, to produce aspool-like shape. This exposes the middle portions of such rods, although they are still set in insulating material, but leaves the end portions of the rod wholly embedded in insulating material.under the rings 53; and it leaves the end portions of such rods round, while reducing the middle portions to approximate half-rounds. The exposed eX- ternal surface of the commutator is accurately ground round, about the axis of the shaft 27, and consists of metal bars alternating with the intervening and embedding insulating material. The glass-hard steel rods which thus constitute the commutator bars are found to withstand wear most effectively,

'even without any lubrication; especially in "portions These blocks 56 may be soldered to the 'spring strips 55; and are made of an'alloy of silver land lead, withthe lead forming be- 130 tween livel (5) and twenty per cent 220%), and most desirably about ten percent 10%) and the silver forming substantially all the remainder of the alloy.

This arrangement of 'commutator and brushes, with the glass-hard high-carbon steel commutator bars 52 and with brushes of the silver-lead alloy, lis found to be eX- 'ceedingly-long-lived, and exceedingly quietA even without lubrication. f

. While the relative amounts" of silver and rather heavy wear on the steel bars 52, strange as that may seem. However, the singing noise is substantially eliminated, and the wear both on the commutator bars and on the blocks 56 is made exceedingly small, if the proportions `of silver and4 lead in. the ,alloy are kept within the range above preferable.

Each brush at its end away from the commutator' is fastened to a clip 60,' which is conveniently of sheet-metal bent into U-shape' cross-section with the base of the U on that indicated s side of the brush which is toward the other brush. Thelegs of the U-section of such clip are divided into two parts, the narrower parts providing fingers 61v which are bent over the strip 55 to clamp firmly, and the wider parts constitute ears 62 which project substantially perpendicularly to the plane of the strip and have outwardly opening notches 63 for cooperating with a brush-supporting rod 64. j

There are two such brush-supporting rods 64, which are mounted in and extend through an insulating supporting block attached to the pole-pieces 31.. The projecting ends of the brush-supporting rods 64 on the opposite side of the insulating supporting block 65 are threaded and carry nuts' 66.to form bindinglposts. On the side toward the commutator, the brush-supportingrods 64 may "be surrounded by insulating spools 67 for part of their length, if desired, to leave eX- posed only the portions which co-operate with the ears 62; and where the rods 64 cooperate with such ears they are provided with circumferential notches 68-into which such ears 62 project. Thus by the co-operation of the notches 68 and the notches 63, the

, brushes are quite accurately positioned on the rods 64 and on the commutator.

The-two brushes 55 are spring-pressedvv apart by a compression spring 70 at theirv ends remote from the commutator. This spring is so attached to the two clips 60, in any suitable manner, that the spring and the two brushes constitute a unit which can be handled as such; but the spring is of course insulated from one or both brushes, as by buttons 71 interposed between 'the springends and the brushes and attached to both. To remove or replace .the brushes, the upper ends thereof are pushed together against the spring 70, as is illustrated in Fig. 9, and first one clip and then the other is either removed or put in place by suitable movements of thev operators thumb and finger. This facilitates inspection and repair. When the brushes are put back, after having been removed, vthey go accurately to their proper position, and in the same accurate (zo-operation with C,the commutator, that has been produced by their grinding, by the positioning effected by the ears 62, notches 63, and notches 68. To lessen the chance of reversing the brushes, oneof the brushes and the corresponding rod 64 are provided with similar identifying marks 72, such as colored dots, indicated as red.

Each particular pair of brushes is associated with a particular commutator, and the v two .ground together, to make an accurate fit of brush against commutator; and by the arrangement that has just been described, this ground fit is made possible of preservation. 1

A' flat non-magnetic shield 75 may be placed above the commutator, extending from one pole-piece 31 to the other.`

The two brush-supporting rods 64 may be i connected to an external circuit, and thence to any suitable current-measuring instrument such `as a recording volt-meter, in any suitable manner. To make such connectiom] without its interfering with the removal of the upper casing-part2l,thelower-casing part is provided on each side with a threaded hole 80, through which the lead-in wire maybe suitably connected to the binding posts formed on the ends of the brush-supporting rods 64.*- The mannerof such connection by way of the holes 80 may be anything desired, but is desirablyby some sort of water-tight and gas-tight arrangement. For instance, there may be conduits 8l, which carry the lead-in wires 82, ofv both of which fragments are shown in Fig. 5; or there may be screwplugs 83 of insulating material, with con-y ducting rods 84 through them, as is indicated in Fig. 4, with such rods 64 provided at both their inner .and outer ends with suitable binding screws 85 for connection of wires leading ishoe magnet hung wholly from said polepieces and having its poles upward, and an armature (zo-operating .with said pole-pieces. 2. A tachometer generator,"compr1s1ng a casing having apartition,` pole-pieces attached to saidpartition, a permanent horseshoe magnet co-operating Vwith said polepieces and havingits polesupward, and an armature (zo-operating with said pole-pieces.

3. A tachometer generator, comprising a casing having a partition,`polepieces attached to said partition, a permanent horseshoe magnet hung wholly from said polepieces, and an armature co-operating with' said pole-pieces.

4. A tachometer` generator, comprising upper and lower casing parts, said lower casing part having an upwardly projecting partition, amagneto generator hung Wholly casing part and geared to said armature shaft, said lower casing'part having bearings for the two shafts and a facing for Vthe attachment of the magneto generator that can all be machined with a single setting of that casing-part.

6. A tachometer generator, comprising a casing, a magneto generator mounted wholly within said casing ,and having the ends of its and geared to said armature In witness whereof, I have hereunto set my hand at Indianapolis, lndiana, this 1st day of October, A. D. one thousand nine hundred and twenty-eight.

DONALD J. ANGUS.

armature shaft also within such casing, and

a` jack shaft separately mounted in said casing and projecting therefrom, and gearing between said two shafts Within the casing, said casing having a unitary removable part the removal of which by itself exposes all of the generator in operation position.

7. A tachometer generator, comprising av casing, a magneto generator mounted wholly within said casing and having the ends of its armature shaft also within such casing, and

a jack shaft separately mounted in 'said casing and projecting therefrom, and gear'- ing between said two shaftswithin thel caslng, said casing being provided with an internal partition which separates the magneto generator and the gearing.

ioo

8. A tachometer generator, comprising a casing, a magneto generator mounted wholly within said casing and having the ends of -its armature shaft also within such casing,

, 'and a jack shaft separately mounted in said casing and projecting. therefrom, and gearing between said` two shafts within the casing, said casing being made in two parts which have a substantially tight joint between them, and said shafts, gearing, and

magneto generator being wholly supported by one .of said part-s so that the removal of the other part does'not affect their relation. 

